extra principals for SSH host certs

modules/services/step-ca/ssh-host.nix

@@ -5,6 +5,12 @@
     provisionerPasswordPath = config.sops.secrets."janus/admin_jwk".path;
     sshKeyPath = "/etc/ssh/ssh_host_ed25519_key";
     sshCertPath = "${sshKeyPath}-cert.pub";
+    mkPrincipalArgs = principals:
+      lib.concatMapStringsSep " " (principal: ''--principal "${principal}"'') principals;
+    principalArgs = mkPrincipalArgs ([
+      cfg.hostname
+      "${cfg.hostname}.john-stream.com"
+    ] ++ cfg.extraPrincipals);
   in
   {
     # NixOS Options
@@ -18,6 +24,11 @@
         type = lib.types.str;
         default = "admin";
       };
+      extraPrincipals = lib.mkOption {
+        description = "Additional SSH host certificate principals to include per host";
+        type = with lib.types; listOf str;
+        default = [ ];
+      };
     };
 
     imports = with inputs.self.modules.nixos; [ ssh ];
@@ -39,8 +50,7 @@
           --host --sign \
           --provisioner "${cfg.provisioner}" \
           --provisioner-password-file "${provisionerPasswordPath}" \
-          --principal "${cfg.hostname}" \
-          --principal "${cfg.hostname}.john-stream.com" \
+          ${principalArgs} \
           "${cfg.hostname}" "${sshKeyPath}.pub"
         '')
         (writeShellScriptBin "ssh-host-cert-check" "${lib.getExe' pkgs.openssh "ssh-keygen"} -Lf ${sshCertPath}")